The present invention relates to an improvement made to false-twist-texturizing techniques and relates more particularly to a novel type of process capable of being implemented on machines enabling partially oriented or unoriented yarns to be treated, at high speed, generally at speeds greater than 1000 m/min, the yarn being drawn during the texturizing operation.
To date, two known techniques, one known by the expression "sequential drawing/texturizing" and the other by the expression "simultaneous drawing/texturizing", are employed on false-twist-texturizing machines, depending on the nature of the yarns treated.
In the "sequential drawing/texturizing" technique, the machine is designed in such a way that the drawing and texturizing operations are carried out in succession in two separate zones. A simple juxtaposition of well-known operations is therefore carried out, which enables the operational conditions both in the drawing zone and the texturizing zone proper to be completely controlled, depending on the nature of the yarns treated. However, this technique has the drawback of leading to machines which are complex and tricky to employ.
Consequently, the technique used most nowadays is the technique called "simultaneous drawing/texturizing" in which the drawing phase is carried out on the yarn in the twisted state upstream of the false-twisting spindle, simply by adjusting the speeds between the two yarn-feed systems provided upstream of the oven and downstream of the false-twisting spindle. However, this technique causes implementation problems, especially in the case of polyester yarns for which it is known to be necessary to control completely the zone where the point of striction occurs.
Now, an improved drawing/false-twist-texturizing process has been found, and it is this which forms the subject of the present invention, which makes it possible not only to retain the advantages of machines employing the simultaneous drawing/texturizing process, but also those of the sequential drawing/texturizing technique, by virtue of which improvement it is possible to localize the point of striction of the yarn during the drawing phase very precisely, this being an absolutely necessary condition especially in the case of treating polyester yarns.